The present applicant is the inventor of the fitted bed sheet described and claimed in U.S. Pat. No. 5,765,241. That sheet, which is fabricated from knit material, is known in the trade as an envelope sheet. It is made from a tube of knit fabric, slit along an edge to form a rectangle. The side margins of the rectangle are then folded inwardly to the midline of the sheet, and top and bottom edges are sewn, joining the top and bottom edges of the folded-over margins to the top and bottom edges of the sheet of fabric. The inwardly directed edges of the margins are then finished with binding in a continuous loop to finish the sheet. The advantages of such a sheet are that it is economical to manufacture, and it fits securely on a mattress, especially a multi-position hospital mattress, without coming off. It lays flat on the mattress, even when the mattress is articulated, which results in a comfortable surface that does not have wrinkles on it to promote bed sores.
The applicant has identified two areas of potential improvement in the envelope sheet. First, the sewing of the top and bottom edges of the folded-over sheet is substantially transverse to the longitudinal axis of the sheet. This does tend to create “ears” of material at the outer edge of the sheet when it is placed on a mattress. These ears tend to be positioned on the side surface of a mattress, near the corners of same. They are untidy looking, and a waste of material. That is, they create the appearance of an ill-fitting sheet.
The other area of improvement lies in the binding that is sewn in a continuous loop around the inward facing edge of the margins. The applicant has developed a technique that eliminates the need for such a binding.